I totally agree. Snape wasn't a good guy, he was spiteful. Voldemort killed Lily, so he helps to kill him. James married Lily, so he tortured Harry. Neville wasn't killed instead so he became the thing he feared the most. Dumbledore couldn't risk you not sticking to his plan so he only told you what to do, nothing else. Minerva was fair to all and honest like all the time, even when she could have gotten fired.